3D reconstruction technology is the basis for the use of virtual reality technology to achieve a complete simulation of the virtual reality world. Therefore, 3D reconstruction technology has always been regarded as the main goal of research in emerging technology fields such as virtual reality. The advanced virtual reality technology is widely used in the correction treatment simulation process, and the correction treatment plan can be designed through intuitive diagnosis and analysis, so that patients and physicians to have an intuitive understanding of the corrective effects they have achieved before the formal start of treatment, which has considerable practical value. This article mainly focuses on the application of 3D modeling in assisted orthodontics. It has a simple understanding of the methods of oral modeling based on relevant data, and then summarizes the specific application of 3D reconstruction technology in orthodontics. In order to further understand the application of 3D technology in dentistry, this article carried out 3D modeling of the oral cavity. Through the modeling of the oral cavity, the difficulties in the application of 3D technology were discovered. Finally, the problems in the modeling process were monitored by experiments, and the experimental results obtained, the first group the average relative measurement accuracy of patients is 1.713%, the second group of patients is 1.690%, and the average relative measurement accuracy corresponding to the previous section is 4.430% and 4.114% (the relative value of the measurement is lower), the accuracy value (means the higher the accuracy).